Gerard Butler Recalls How He 'Almost Killed' Hilary Swank While Filming 'P.S. I Love You'

"She had to get taken to the hospital," Gerard Butler detailed of an on-set accident that occurred while he and Hilary Swank filmed the 2007 romance.

Gerard Butler is recalling the moment when he "almost killed" Hilary Swank on the set of P.S. I Love You.

While appearing on The Drew Barrymore Show Tuesday, the actor, 53, revealed to host Drew Barrymore that he injured Swank, 48, while the pair were working on a scene in the 2007 film where he danced "like an idiot" in boxer shorts and a pair of suspenders.

Detailing that his character, Gerry Kennedy, was supposed to get hit in the face with the suspender clip while getting undressed during one part of the film, Butler said the piece took off and hit Swank's head instead.

"It gets stuck, it releases [and] flies over my head, hits her in the head — slashes her head," he explained. "I cut her open. You could even see the teeth [of the clip]. She had to get taken to the hospital."Added Butler: "Imagine this studio, and in three seconds, everybody's gone. And I'm just sitting there in my Irish [shamrock] boxer shorts and my boots and a pair of socks, and I just started crying. I scarred Hilary Swank. I almost took her eye out, and I just made a fool of myself for two days."

P.S. I Love You, which was directed by Richard LaGravenese and based on the 2004 novel of the same name by Cecelia Ahern, follows a widow who learns of 10 messages that her late husband left her after his death to help her move on.

Alongside Butler and Swank — who is currently pregnant and expecting twins with husband Philip Schneider — the film also stars Lisa Kudrow, Gina Gershon, James Marsters, Harry Connick Jr. and Jeffrey Dean Morgan.

Butler also explained during his chat with Barrymore, 47, that he went into filming P.S. I Love You with the intention of putting Swank's needs first.

"I remember saying to the director, I'm not going to think about myself in this movie, I'm only going to think about her," he said. "Make sure she's okay, she's cool, because that's kinda who this [character] was, and it made the experience so much more fun."

"When I got out of ... [the] actor, self-obsessed, how am I doing [state of mind], I actually was more like, 'How is she doing?' " Butler continued, then calling Swank "so cool and so great to work with."